Forum: Ruby-dev [Open] TracePoint can invoke inconsistent call event with bmethod

308cbef6e86dfc49cce3b2d4cf42aedc?d=identicon&s=25 unknown (Guest)
on 2014-06-19 12:47
(Received via mailing list)
Issue #9959 has been reported by Koichi Sasada.

----------------------------------------
Bug #9959: TracePoint can invoke inconsistent call event with bmethod
https://bugs.ruby-lang.org/issues/9959

* Author: Koichi Sasada
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* Category: core
* Target version: current: 2.2.0
* ruby -v: 2.2
* Backport: 2.0.0: REQUIRED, 2.1: REQUIRED
----------------------------------------
define_method で定義したメソッド(以降、bmethod)を実行するとき、引数のエラーがあったとき、call
イベントのみ発生し、return イベントが発生しない、という問題がありました。

```ruby
  define_method(:method_test_argument_error_on_bmethod){|correct_key:
1|}

  def test_argument_error_on_bmethod
    events = []
    curr_thread = Thread.current
    TracePoint.new(:call, :return){|tp|
      next if curr_thread != Thread.current
      events << [tp.event, tp.method_id]
    }.enable do
      begin
        method_test_argument_error_on_bmethod(wrong_key: 2)
      rescue => e
        # ignore
      end
    end

    assert_equal [], events # should be empty.
  end
```

今だと、次のようになります。

```
TestSetTraceFunc#test_argument_error_on_bmethod
[test_settracefunc.rb:1258]:
<[]> expected but was
<[[:call, :method_test_argument_error_on_bmethod]]>.
```

これは、Proc を実行する前に TracePoint(call) を発生するが、
例外で戻ろうとしたときに、まだ Proc が起動しておらず、フレームに情報がないため、
return イベントが発生しないため、起こります。

これを解決するために、bmethod 用の call/return イベントを発生する場所を調整しました。

```diff
Index: vm.c
===================================================================
--- vm.c  (revision 46463)
+++ vm.c  (working copy)
@@ -715,15 +715,17 @@
         const rb_block_t *blockptr, const NODE *cref,
         VALUE defined_class, int splattable)
 {
-    if (SPECIAL_CONST_P(block->iseq))
+    if (SPECIAL_CONST_P(block->iseq)) {
   return Qnil;
+    }
     else if (BUILTIN_TYPE(block->iseq) != T_NODE) {
+  VALUE ret;
   const rb_iseq_t *iseq = block->iseq;
   const rb_control_frame_t *cfp;
   int i, opt_pc, arg_size = iseq->arg_size;
-  int type = block_proc_is_lambda(block->proc) ?
-    VM_FRAME_MAGIC_LAMBDA : VM_FRAME_MAGIC_BLOCK;
-
+  int type = block_proc_is_lambda(block->proc) ? VM_FRAME_MAGIC_LAMBDA
: VM_FRAME_MAGIC_BLOCK;
+  const rb_method_entry_t *me = th->passed_bmethod_me;
+  th->passed_bmethod_me = 0;
   cfp = th->cfp;

   for (i=0; i<argc; i++) {
@@ -733,7 +735,7 @@
   opt_pc = vm_yield_setup_args(th, iseq, argc, cfp->sp, blockptr,
              (type == VM_FRAME_MAGIC_LAMBDA) ? splattable+1 : 0);

-  if (th->passed_bmethod_me != 0) {
+  if (me != 0) {
       /* bmethod */
       vm_push_frame(th, iseq, type | VM_FRAME_FLAG_FINISH |
VM_FRAME_FLAG_BMETHOD,
         self, defined_class,
@@ -740,8 +742,10 @@
         VM_ENVVAL_PREV_EP_PTR(block->ep),
         iseq->iseq_encoded + opt_pc,
         cfp->sp + arg_size, iseq->local_size - arg_size,
-        th->passed_bmethod_me, iseq->stack_max);
-      th->passed_bmethod_me = 0;
+        me, iseq->stack_max);
+
+      RUBY_DTRACE_METHOD_ENTRY_HOOK(th, me->klass, me->called_id);
+      EXEC_EVENT_HOOK(th, RUBY_EVENT_CALL, self, me->called_id,
me->klass, Qnil);
   }
   else {
       vm_push_frame(th, iseq, type | VM_FRAME_FLAG_FINISH,
@@ -756,7 +760,15 @@
       th->cfp->ep[-1] = (VALUE)cref;
   }

-  return vm_exec(th);
+  ret = vm_exec(th);
+
+  if (me) {
+      /* bmethod */
+      EXEC_EVENT_HOOK(th, RUBY_EVENT_RETURN, self, me->called_id,
me->klass, ret);
+      RUBY_DTRACE_METHOD_RETURN_HOOK(th, me->klass, me->called_id);
+  }
+
+  return ret;
     }
     else {
   return vm_yield_with_cfunc(th, block, self, argc, argv, blockptr);
Index: vm_insnhelper.c
===================================================================
--- vm_insnhelper.c  (revision 46462)
+++ vm_insnhelper.c  (working copy)
@@ -1615,17 +1615,11 @@
     rb_proc_t *proc;
     VALUE val;

-    RUBY_DTRACE_METHOD_ENTRY_HOOK(th, ci->me->klass,
ci->me->called_id);
-    EXEC_EVENT_HOOK(th, RUBY_EVENT_CALL, ci->recv, ci->me->called_id,
ci->me->klass, Qnil);
-
     /* control block frame */
     th->passed_bmethod_me = ci->me;
     GetProcPtr(ci->me->def->body.proc, proc);
     val = vm_invoke_proc(th, proc, ci->recv, ci->defined_class,
ci->argc, argv, ci->blockptr);

-    EXEC_EVENT_HOOK(th, RUBY_EVENT_RETURN, ci->recv, ci->me->called_id,
ci->me->klass, val);
-    RUBY_DTRACE_METHOD_RETURN_HOOK(th, ci->me->klass,
ci->me->called_id);
-
     return val;
 }

```

これも、2.1, 2.0 で再現します。
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